Re: [kernel-hardening] Re: [PATCH 2/2] mm: restrict access to/proc/meminfo

[Vasiliy Kulikov]

On Thu, Sep 29, 2011 at 12:57 -0400, Valdis.Kletnieks@xxxxxx wrote:
> But now he has to fly blind for the next 30 because the numbers will display
> exactly the same, and he can't correct for somebody else allocating one so he
> needs to only allocate 29...

You're still talking about "slabinfo", which is already restricted.


And meminfo can be still learned with the same race window (ala seq lock):

    prepare_stuff();
    fill_slabs(); // Here we know counters with KB granularity
    while (number_is_not_ok()) {
        prepare_stuff();
        fill_slabs();
    }
    do_exploit();


Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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